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Adult T-cell leukemia/lymphoma (ATLL) is a malignancy of mature T-cell origin with multi-organ involvement. Because the chemokine receptors play crucial roles in tissue-specific homing of mature lymphocytes, particular chemokine receptors expressed on ATLL cells may be involved in their tissue infiltration. We thus performed a comprehensive survey on the chemokine receptor expression in ATLL. ATLL cells expressed transcripts of CCR1, CCR4, CCR7, CCR8, CCR10 and CXCR4 but hardly expressed those of CCR2, CCR3, CCR5, CCR6, CCR9, CXCR1, CXCR2, CXCR3 and CXCR5. These results were confirmed at the protein level by flow cytometric analysis. Notably, patients who have skin lesions showed significantly higher levels of CCR10 mRNA expression than patients without skin lesions. ATLL cells migrated efficiently to the CCR4 ligand, CCL22, and moderately to the CCR10 ligands, CCL27 and CCL28. Moreover, ATLL skin lesions consistently contained transcripts of CCR10 and its ligands CCL27 and CCL28 besides those of CCR4 and its ligands CCL17 and CCL22 that have been reported previously. Collectively, the frequent co-expression of CCR4 and CCR10, the known pair of skin-homing chemokine receptors, may play an important role in ATLL invasion into the skin.

Interleukin-15 receptor (IL-15R) and IL-2R have the same beta and gamma chains, but IL-15R has a specific alpha chain distinct from that of IL-2Ralpha, which is indispensable for the high affinity binding of IL-15. In the present study, we examined four IL-2-dependent adult T-cell leukemia (ATL) cell lines for their IL-15R expression. All cell lines bound IL-15, which was not inhibited by a 100-fold excess amount of IL-2, proliferated in response to IL-15 to the same degree as to the stimulation with IL-2, and were maintained without IL-2. The responses to 1L-15 were inhibited by the antibodies against IL-2R beta or gamma chains but was not by the IL-2R alpha chain antibody. [125I]-IL-15 exhibited a single high-affinity binding with an apparent kd of 0.17 nmol/L. Reverse transcription-coupled polymerase chain reaction (RT-PCR) showed that the cell lines had the mRNA of IL-15R alpha. The cell lines also had IL-15 mRNA. Despite the presence of IL-15 mRNA, the cell lines did not secrete IL-15, and the culture supernatants of fresh ATL cells and plasma from the patients did not contain a detectable amount of IL-15 with a few exceptional cases, although fresh ATL cells also responded to IL-15. These results suggest that ATL cells have the complete form of IL-15R and respond to IL-15. Such an IL-15-dependent cell proliferation mechanism might be used in the development of ATL and for the invasion and proliferation of ATL cells in the visceral organs.

The expression and function of the Fas-receptor (Fas-R) were examined in chronic lymphocytic leukaemia (CLL), hairy cell leukaemia-variant (HCL-v) and adult T-cell leukaemia (ATL). The expression of Fas-R in freshly isolated leukaemic cells was qualitatively and quantitatively different between each disease; faint in B-CLL, moderate in HCL-v and strong in ATL. Both full-length and alternatively spliced truncated forms of Fas mRNA were detected even in CLL B cells with faint to negative Fas-R, and Fas mRNA was also shown to be capable of increasing in vitro expression, i.e. the message was functional. In contrast, Fas-R expression on ATL cells was heterogenous and usually intense with a mean density approximately 3-fold higher than that of normal T cells. Fas-R was confirmed to have the potential function for anti-Fas monoclonal antibody-mediated cell death in vitro in Fas-R+ ATL cells. The expression level of Fas-R on the cells was higher in chronic than acute ATL (10,360 v 6260 antibody-binding capacity per cell, mFasABC; P<0.05) and was inversely correlated with serum LDH activity, suggesting that the strong Fas-R accounts for the slow progression of chronic ATL and the negative Fas-R protects from Fas-mediated cell death. These results show that Fas-R expression on leukaemic cells is valuable in their characterization and perhaps their function, and may contribute to the progression and immune evasion of malignant clones.

Fas, also designated as Apo-1 and CD95, is a cell membrane receptor (mFas) involved in apoptotic cell death. A soluble form (sFas) lacking the transmembrane domain due to alternative splicing has been isolated. Abnormal expression of sFas and mFas is likely to be involved in lymphoproliferative disorders and auto-immune diseases. Adult T-cell leukemia (ATL) caused by human T-cell-leukemia virus type-1 (HTLV-1) is well known to be a T-cell neoplasm with strong mFas expression, suggesting a role of Fas in the pathology of the disease. We examined protein and mRNA expression of the 2 isoforms of Fas in fresh ATL cells and ATL cell lines. In general, mFas was strongly expressed in ATL cells, and sFas levels in sera were high, especially in malignant ATL. However, expression of the isoforms in some cases of ATL varied; there was no mFas expression on the cell surface and sFas levels were high in serum. In contrast, all ATL cell lines examined showed strong mFas expression and scarce production of sFas in the supernatant, corresponding to strong expression of full-length Fas mRNA and weak to negative expression of alternatively spliced mRNA lacking the transmembrane domain. Our findings indicate that the mode of expression of Fas isoforms in ATL cells is not always homogenous and that Fas may play a role in the malignant behavior and oncogenesis of ATL.

We examined 111 patients with acute type- or lymphoma type-adult T-cell leukemia (ATL) and compared them with 106 patients with non-Hodgkin's lymphoma (NHL). In addition to skin involvement and hypercalcemia which are already known to be frequent in ATL, ATL patients showed an higher incidence of hepatic involvement. There was more frequent palpable hepatomegaly, higher total bilirubin, GOT, GPT, lactate dehydrogenase (LDH), and alkaline phosphatase values in ATL than in NHL patients (p < 0.0001). Among 36 autopsied liver samples, invasion of ATL cells was confirmed in 22 cases. ATL patients with impaired hepatic function showed shorter survival times than patients without hepatic dysfunction. Moreover, ATL patients showed a worse performance status (PS), a higher incidence of lytic bone lesions, lower total protein (TP) and serum albumin levels than NHL patients. This invasive characters of ATL cells and consequent impaired general condition seemed to be factors affecting the poor prognosis recorded in ATL.

We established IL-2-dependent T cells from an adult T-cell leukaemia (ATL) patient whose leukaemic cells changed from CD4 single-positive in the initial phase to double-negative (CD4- CD8-) at the time of exacerbation. The cells termed SO-4 were of ATL cell origin and showed the double-negative TCR alpha beta/CD3+ T-cell phenotype. SO-4 cells acquired CD4 antigen expression following stimulation with concanavalin A (ConA) or immobilized anti-CD3 antibody. The induction was inhibited by herbimycin A, an inhibitor of protein tyrosine kinase (PTK) activity. No CD4 mRNA was detectable in unstimulated SO-4 cells but a 3.0 kb signal specific for CD4 mRNA was detected after stimulation. These findings indicate that SO-4 cells return to their original phenotype (CD4 single-positive) by stimulation involving PTK. The results indicate that there is a pathway of phenotypic cycling between CD4 single-positive and double-negative T cells.

To clarify the biological characteristics of adult T-cell leukemia (ATL), immunophenotyping and DNA aneuploid analysis were performed in 72 ATL cases, using flow cytometric techniques. DNA aneuploidy was found in 45 cases (62.5%); the DNA index ranged from 1.03 to 2.16 (mean: 1.24). The incidence of aneuploidy in smoldering, chronic, acute, and lymphoma ATL subtypes was 20.0%, 46.6%, 76.3%, and 77.8%, respectively. The aneuploid patients had a greater tumor burden (adenopathy, hepatosplenomegaly, and leukocytosis with ATL cells), a higher level of serum LDH, and a higher incidence of hypercalcemia, compared with the diploid group. Further, unusual aberrant immunophenotypes were identified predominantly in the aneuploid group. Patients with aneuploidy had a 7.6 month median survival time (MST) with a 2 year survival rate of 24.6%, significantly worse than in the patients with diploidy, whose MST was 25.4 months with a 2 year survival of 60.1%. In some aneuploid patients, the disease often progresses from a static to an aggressive form. Thus, the determination of aneuploidy and unusual immunophenotype should be useful for detecting clinical behavior and for monitoring ATL patients, particularly in regard to such progression.

We describe 4 cases of adult T-cell leukemia (ATL) with unusual morphology and aberrant immunophenotype. All patients were Japanese and born in the Nagasaki district, an area endemic for HTLV-I. Peripheral blood and/or bone marrow films revealed bizarre giant cells with and without large nucleoli; the cells were 5 to 6 times the diameter of erythrocytes, resembling Hodgkin's cells. Some peripheral blood cells were morphologically similar to prototypic ATL cells, while many other cells in the bone marrow showed unusual morphology. Furthermore, leukemic cells had aberrant immunophenotypes such as the CD8-positive type in patients 1 and 2, the CD4-.CD8- double-negative type in patient 3, and the CD5 antigen defect in patient 4. All patients had marked elevations of the serum calcium and LDH and organomegaly, while all had a short survival. Anti-HTLV-I antibodies and provirus DNA monoclonality were demonstrated in all patients. The results suggested that the unusual morphology and aberrant ATL cell immunophenotype may be indicative of a high grade malignant behaviour of ATL.

Cases of adult T-cell leukemia/lymphoma (ATLL) display several peculiar clinical features, including skin rash, hypercalcemia, and an increase in the absolute neutrophil count. The patients rarely have pronounced eosinophilia. In this study, the eosinophilia observed in lymphoproliferative disorders of 62 patients with ATLL, 27 with T-cell lymphoma (TL), and 19 with B-cell lymphoma (BL) was investigated. The incidence of eosinophilia (greater than or equal to 570/microliters) was higher in patients with ATLL than in patients with TL or BL. Thirteen patients with ATLL (21.0%), 3 with TL (11.1%), and 2 with BL (10.5%) had eosinophilia. Of these patients, three with ATLL and one with TL who had a pathologic diagnosis of immunoblastic lymphadenopathy (IBL) showed pronounced eosinophilia up to 10,934/microliters. Because the number of eosinophils in the peripheral blood of these patients correlated both with the number of ATLL cells and the degree of lymphadenopathy and because this fluctuated with chemotherapy, it seems likely that the secretion of some lymphokines by the lymphoma cells is responsible for the eosinophilia.

We examined phenotypically 107 patients with adult T-cell leukemia (ATL), using a panel of monoclonal antibodies, in order to clarify the occurrence of aberrant phenotypes, and to determine the correlation between phenotypic diversity and prognosis. The incidence of the typical (CD4+.CD8-) phenotype, the double-negative (CD4-.CD8-), the double-positive (CD4+.CD8+), and the CD8-positive (CD4-.CD8+) phenotypes was 81%, 7%, 7%, and 4%, respectively. The median survival time (MST) for all patients was 10.0 months with 17% survival at 2 years. The patients with typical phenotypes had a 10.2 month MST with 20% survival at 2 years, significantly better than the patients with the unusual phenotypes whose MST were 4.9, 7.8, and 2.6 months, respectively, for the double-negative, double-positive, and CD8-positive phenotypes. Lack of antigens reactive with CD2, CD3, CD5, and WT31 monoclonal antibody panels was one factor in bad prognosis, but the presence of CD4 and CD8 antigen abnormalities was much more significant.

The authors examined peripheral blood samples from patients with adult T-cell leukemia (ATL) using the monoclonal antibody Ki-67 which detects a nuclear antigen present in actively proliferating cells. In patients with chronic ATL, the percentage of Ki-67-positive cells was significantly lower than in acute ATL patients (median values, 3.3% versus 18.9%, P less than 0.001). Furthermore, there was a significant inverse correlation between the percentage of Ki-67-positive cells and the length of survival (P less than 0.001). Serum lactic dehydrogenase (LDH) levels also showed a significant inverse correlation with survival, but this was less strong than that for Ki-67 (0.01 less than P less than 0.02). Thus, Ki-67 positivity appears to indicate the aggressiveness of ATL, and can possibly be used for the clinical classification of ATL patients as well as for the prediction of prognosis.